The development name for Mozilla Firefox 3 is Gran Paradiso. The precursory releases were codenamed "Minefield", as this was the name of the trunk builds. "Gran Paradiso" (trans. "Great Paradise"), like other Firefox development names, is an actual place; in this case the highest mountain group in the Graian Alps. With the releases of version 3.0 alpha 1 on December 8, 2006 and version 3.0 alpha 2 on February 7, 2007, it adopted the "Gran Paradiso" codename. A post on the Mozilla Wiki "Release Roadmap" from President of Products Christopher Beard suggests a release in November 2007.
The largest known change for Firefox 3 is the implementation of Gecko 1.9, an updated layout engine. It will also provide CSS3 columns. Firefox 3 will include features that were bumped from Firefox 2, such as the overhauled Places system for storing bookmarks and history in an SQLite backend, according to the wiki. Due to lack of support for Windows 95, Windows 98, Windows Me, and Windows NT 4.0 in Cairo, and because Microsoft decided to end support for Windows 98 and Windows Me on July 11, 2006, Firefox 3 will not run on those operating systems. Firefox 3.0 for the Mac OS will only run on version 10.3.9 or higher. Unlike previous versions, Firefox 3 on Mac OS X will use a Cocoa widget implementation.
There is also advanced ongoing work focused on further implementation of features from WHATWG specification. In particular, support for the controversial "ping" attribute in and HTML elements is implemented and enabled by default. The purpose of this additional attribute is tracking clicking on links. LWN.net notes that "ping" has advantages over current click-tracking techniques because it can more reliably get the user to their intended destination and the user has the option of turning the "ping" feature off. The development team is asking users to submit feature requests that they wish to be included in Firefox 3.